Supervisory device for communication apparatus



June 26, 1951 M. G. FAVRE 2,558,129

SUPERVISORY DEVICE FOR COMMUNICATION APPARATUS Filed June 21, 1945 2 Sheets-Sheet l F9. TRA/VSM/TTER 2 All/QM comma KEYED TRANSMITTER I I I I i l I I I I I I I I I I I I I l I l I I I www- June 26,1951

M. G. FAVRE SUPERVISORY DEVICE FOR COMMUNICATION APPARATUS Filed June 21, 1945 2 Sheets-Sheet z I 56 K5750 400/0 /57 7RA/YSM/77El? I M4 07 msm/e 53 Patented June 26, 1951 SUPERVISORY DEVICE FOR COMMUNICA- TION APPARATUS Marcel Georges Fayre, Wettingen, Switzerland, assignor to Patelhold "Patentvcrwertungs- & 'Elektro Holding A.-G., 'Glarus, Switzerland Application June 21, 1945, Serial No. 600,737 In Switzerland July 1, 1944 10 Claims.

1 It is known to equip the safety devices provided in a transmitter, for instance the maximum and minimum current relays, with a fault indicator, so that a warning signal draws attention to any abnormal conditions. Despite this it is, however, essential that the modulation should be checked. For this purpose a part of the antenna power can be supplied to a control receiver. Continuous supervision is then necessary and when an interruption occurs it is also essential to determine whether this is due to a defect in the transmitter or to a modulation pause.

These drawbacks are overcome according to'the present invention which concerns a supervisory device for communication sets, particularly high frequency transmitters, the aforesaid device being located outside the parts which have to be supervised. The characteristic feature of the invention is that means are provided for comparing at least one characteristic Value formed from the output signal of the communications set with a control signal supplied to the set.

A great advantage of the inventionis that'the assembly is very simple, and when compared with known devices used for the 'same purpose very few auxiliary elements are required. Furthermore the kind 'of fault 'can be determined without any switching over. Also changes in the circuits, such as for instance too large or too small a carrier'oscillation, are also indicated;

A number 'of constructional examples of the invention are illustrated in the accompanying drawings. Fig. 1 shows the basic diagram of connections, Fig. 2 the arrangement of a simple supervisory device for telegraphy, Fig. 3 an arrangement for supervisory control with modulated telegraphy, and Fig. 4 an arrangement "as applied to a transmitter for telephony.

The main feature of the invention is thatth'e control signals supplied to the transmitter I (Fig. 1) and causing modulation or keyin are also passed to a control device 2. Part of the output signal of the transmitter also reachesthe control device 2. Supervision is achieved by comparing both signals.

Fig. 2 shows a simple supervisory device for a telegraph transmitter. The control deviceis again indicated by the reference numeral 2. Part of the power of the transmitter antenna [5 is passed to the control device Zoverthe condenser 16 and the high frequency cable 4. This power produces an alternating voltage in coil 5 which is'rectified b'yxthe double diode 6. The resulting direct current flow through one 'half I '01 the aerial current disappears.

differential relay 8 which actuates the contact 9. The second coil [0 of relay 8 is supplied with anode current from tube l I. This current is controlled by the grid voltage supplied to grid l3 from point l2. A variable resistance I4 is provided 'for regulating the anode current. When keying, the supply to coil Hi can be interrupted in rhythm with the keying for instance by means of a contact between the conductor and earth.

When the antenna radiates high frequency power then there is also an alternating voltage at the ends of coil 5, so that a direct current fiows through coil l. This disappears when the If during keying grid [-3 is also controlled, then a current will flow simultaneously through windings l and I0, and if these currents are made equal by adjusting resistance is, then relay 8 will not drop out during operation, on condition that the power radiated-from antenna l5 varies in rhythm with the control voltage supplied at l2. Relay 8 can for instance be-adjusted to operate at a current difference of 15% and actuates an alarm device such as a bell, lamp, and the like. Many different arrangements are or" course possible for varying the voltage supplied to point l2 in rhythm with the keying pulse and hence this control has simply been shown in block schematic in Fig. 2. The keying means is indicated by rectangle 5| and the keyin voltage pulses which are fed to transmitter I over line connection 52 can also be fed over line connection 53 to grid terminal l2. Thus'each time the transmitter l i keyed, the correspondingly effected change in the anode-cathode circuit of tube ll causes the current in coil 10 of relay 8| to vary rhythmically with the rise and fall of the current in the other coil 1 of this relay, assuming of course that the power radiated from antenna 15 is in rhythm with the keying input pulses from the keying means 5 l.

Undercertain circumstances the anode voltage of tube H can change proportionally with the high voltage of the'tubes of the last stage of the transmitter, so that the currents in windings 'l and I0 remain unchanged for different adjustmentsof the high voltage rectifiers. A measuring instrument can also be provided for measuring the current in winding 1. In orderto obtain an acoustical control this current can also be used to control a low frequency oscillator-which feeds a loud speaker. The double diode 6 does not necessarily have'to be combined with an amplifier tube to form a single tube; instead two separatetubes can be provided.

The arrangement shown in Fig. 3 can be used with modulated telegraphy. Elements which correspond to those shown in Fig. 2 are indicated by the same reference numerals. The necessary output energy is supplied from an auxiliary antenna 33. In order to understand the method or" operation of the other elements it is necessary above all to consider the parallel connection of resistance 2| with capacitance 22. The current rectified by the diodes 6 flows through resistance 21. Capacitance 22 is so dimensioned that the high frequency carrier oscillations are smoothed, whilst the audio frequencies with which these oscillations are modulated produce an alternating voltage at the ends. This alternating voltage is transmitted over condenser 23 to potentiometer 24 and a suitable fraction of same is passed to the control grid of tube 25. The anode current fiows through the primary winding of transformer 3d. The secondary current rectified by rectifier 2i and smoothed by capacitance 31 flows through coil 28 of relay 29. The other half of the relay also has a current from coil 1 of relay 8 flowing through it.

It is clear that when there is an audio-frequency amplitude modulation in the output signal of the transmitter an alternating voltage with variable audio-frequency will occur at resistance 2i and thus also at resistance 24, this voltage being suitably amplified in tube 25. A direct current thus flows in part 28 of relay 29. The effect of this current on contact 3| is compensated by the current in coil I which is in series with coil 35. If a disturbance occurs so that there is no audio-frequency amplitude modulation of the output signal of the transmitter, a current will flow through coil 36 but not through coil 28, and contact 3| is actuated.

If the antenna does not radiate any high frequency at all, although the transmitter is keyed so that there is a control voltage at I2, relay 29 does not operate because there is no current flowcauses a current to fiow in the winding W, the .effect of which is not compensated because no current flows through coil '1.

A loud-speaker 32 can be provided for the purpose of a further control. Instead of comparing the current of the relay halves i and 23, it is also possible to compare that of relay halves I and 23; that is coil it) instead of coil i has to be connected in series with coil 36. In this case both relays will be in the alarm position when there is no output signal. The current in the coil of relay 29 can be indicated by special instruments.

Fig. 4 shows a supervisory arrangement for a telephony transmitter. The method of operation is more or less the same as that described in connection With Fig. 3.

The output signal of the transmitter which is supplied over conductor 4 and is part of the high frequency power supplied to antenna i5, is rectified and again forms the current flowing through one half of relay 8. At the same time as a carrier wave is radiated a control voltagev obtained from the keying circuit is applied to terminal [2 which causes a current to flow in the anode circuit and coil lo and has a magnitude equal to the average current in coil 1. It is understood of course that during broadcast operation, transmitter i will be keyed continuously from the keying means 5| to thereby provide the necessary continuous carrier wave while the audio signals for modulating the carrier are fed to transmitter i over line connection 55 from the audio input 51.

The voltage at the capacitance 22 and resistance 2i controls the anode current of tube 25. This flows through the primary winding of transformer 4i and the secondary current of the latter is rectified by rectifier 42 and smoothed by condenser 43. By this means when there is a speechfrequency modulation a direct current flows through coil 4% of relay 45, this current being indicated by an instrument if desired.

In order that an equally large current should flow simultaneously through coil 46 part of the power represented by the speech at input lead 55 is supplied to the control grid of tube 41 over line connection 56 and potentiometer 49. After amplification, rectification and smoothing, a further current is obtained which prevents relay 45 being actuated by coil 3 No current flows to relay 45 when the transmitting microphone is not spoken into. If on the other hand due to a disturbance there is no modulation of the carrier, although speech currents are supplied to the inet of the transmitter, then only part as is under current and relay .5 is actuated. Potentiometers 24 and 49 serve to adjust mutually the currents of relay 45. If desired a loudspeaker 58 can also be provided for control purposes.

The invention is not restricted to transmitters. It can also be used with transmission devices, amplifiers, and modulators. When suitable alterations are made it can also be used with frequency and time modulation instead of amplitude modulation. Instead of differential relays other compensation methods or devices can be employed which control the current differences. It is of course also possible to replace the amplifier tube i l with double diode by two tubes. Tubes of this kind can also be used as rectifiers, for instance tubes arranged in bridge connection.

I claim:

1. In a supervisory system for radio communication apparatus, in combination, means including a tube type rectifier coupled to the output of said apparatus for deriving a rectified signal accordingly, an electron tube having cathode, plate and control grid elements, means applying a voltage to .the grid of said tube, said voltage bein derived from the control signal applied to the input to said apparatus, a differential relay, and means connecting the coils of said relay in the cathode circuits respectively of said electron and rectifier tubes such that said coils receive equal currents only when the output characteristic of said apparatus matches that of the control sig- .nal input.

2. A supervisory system for radio communication apparatus as defined in claim 1 wherein said rectifier and electron tubes are combined in a single envelope with a common cathode.

3. In a supervisory system for a radio telegraph transmitter in which the carrier wave is keyed with an audio modulation signal, in combination, means coupled to the output of said transmitter for deriving a first signal characteristic of the said transmitter, said third signal being characteristic of the keying state of the transmitter, means comparing said first and third signals,

means comparing said first and second signals, and alarm control means actuated in response to any difference arising in said compared signals.

4. In a supervisory system for a radio frequency telegraph transmitter in which the carrier wave is interrupted in accordance with a keyed input signal, in combination, a rectifier tube coupied to the output of said transmitter for deriving a direct current proportional to the amplitude of the radiated carrier wave, an electron tube containing plate, cathode and grid elements, means deriving a voltage for said grid from the keyed input signal, and a dual coil differential alarm relay having one coil connected in the cathode circuit of said rectifier and the other coil connected in the cathode circuit of said tube, said coil currents being of like magnitude and phase only when the carrier wave interruptions agree with the keyed input signal.

5. In a supervisory system for a radio telegraph transmitter in which the carrier wave is keyed with an audio modulation signal, in combination, a tube rectifier coupled to the output of said transmitter for deriving a direct current proportional to the amplitude of the audio modulated carrier wave, an electron tube containing plate, cathode and grid elements, means deriving a voltage for said grid from the keying circuit for said transmitter, means also coupled to the transmitter output for deriving a voltage signal proportional to the average amplitude of the audio frequency modulation voltage of said output, a pair of dual coil differential alarm relays, means connecting a coil of each relay in the cathode circuit of said rectifier, means connecting the other coil of one relay in the cathode circuit of said electron tube, and means applying a current to the other coil of the other relay proportional to said voltage signal.

6. In a supervisory system for audio modulated telegraphy transmitter apparatus, in combination, means including a rectifier coupled to the output of said transmitter for deriving a signal characteristic of the transmitter carrier Wave, a condenser in parallel with a resistor connected in the output of said rectifier for producing a A means deriving a current signal from the keyed input to said transmitter characteristic of the keying state of the transmitter, a pair of diiferential relays, means connecting the output of said first rectifier to one coil of each of said relays, means connecting the output of said second rectifier to the other coil of one of said relays, and means connecting said current signal to the other coil on the other of said relays.

7. In a supervisory system for radio telephony transmitter apparatus, in combination, means including a rectifier device coupled to the output of said transmitter for deriving a rectified signal characteristic of the transmitter carrier wave, means deriving a second signal characteristic of the keying condition of said transmitter, means deriving a third signal from said transmitter output proportional to the average amplitude of the low frequency modulation voltage of the output, means deriving a fourth signal proportional to the average amplitude of audio frequency modulation input to said transmitter, means comparing said first and second signals, means comparing said third and fourth signals, and alarm control means actuated in response to any difference arising in said compared signals.

8. In a supervisory system for a radio transmitter, in combination, means including a rectifier coupled to the output of said transmitter for deriving a rectified current characteristic of the transmitter output, an electronic control tube having cathode, plate and control grid elements, means applying a voltage to the grid of said control tube, said grid voltage being varied in accordance with the control signal applied to the input to said transmitter, a dual coil differential relay, means connecting the output of said rectifier to one of the coils of said relay, and means connecting the other relay coil in the space current circuit of said control tube.

9. In a supervisory system for a radio telegraph transmitter in which the carrier wave is keyed with an audio modulation signal, in combination, a rectifier coupled to the output of said transmitter for deriving a current proportional to the amplitude of said carrier wave, a control tube having plate, cathode and grid elements, means deriving a voltage for said grid from the keying circuit for said transmitter, means also coupled to the transmitter output for deriving a current signal proportional to the amplitude of the audio frequency modulation voltage of said output, means continuously comparing said rectified current with the space current of said control tube and means continuously comparing said rectified current with said current signal.

10. In a supervisory system for audio modulated telegraphy transmitter apparatus, in combination, means including a rectifier coupled to the output of said transmitter for deriving a signal characteristic of the transmitter carrier wave, a condenser in parallel with a resistor connected in the output of said rectifier for producing a voltage across the resistor characteristic of the audio frequency component of the transmitter output, a second rectifier fed by said voltage, means deriving a current signal from the keyed input to said transmitter characteristic of the keying state of the transmitter, means continuously comparing the outputs from said first and second rectifiers, and means continuously comparing the output from said first rectifier with said current signal.

MARCEL GEORGES FAVRE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,604,610 Schelleng Oct. 26, 1926 2,049,948 Cushman Aug. 4, 1936 2,066,522 Doherty Jan. 5, 1937 2,085,125 Shaw June 29, 1937 2,159,020 Ferrell May 23, 1939 2,272,768 Crosby Feb. 10, 1942 2,338,556 Weldon Jan. 4, 1944 

